Biomedical subjects

R C Melo

Publications and source records attributed to R C Melo.

8 recordsLinked to original sources

PubMed2006

The Star STING server: a multiplatform environment for protein structure analysis.

Star STING is the latest version of the STING suite of programs and corresponding database. We report on five important aspects of this package that have acquired some new characteristics, designed to add key advantages to the whole suite: 1) availability for most popular platforms and browsers, 2) introduction of the STING_DB quality assessment, 3) improvement in algorithms for calculation of three STING parameters, 4) introduction of five new STING modules, and 5) expansion of the existing modules. Star STING is freely accessible at: http://sms.cbi.cnptia.embrapa.br/SMS/, http://trantor.bioc.columbia.edu/SMS, http://www.es.embnet.org/SMS/, http://gibk26.bse.kyutech.ac.jp/SMS/ and http://www.ar.embnet.org/SMS.

Algorithms↗

PubMed2005

Effects of age and physical activity on the autonomic control of heart rate in healthy men.

The effects of the aging process and an active life-style on the autonomic control of heart rate (HR) were investigated in nine young sedentary (YS, 23 +/- 2.4 years), 16 young active (YA, 22 +/- 2.1 years), 8 older sedentary (OS, 63 +/- 2.4 years) and 8 older active (OA, 61 +/- 1.1 years) healthy men. Electrocardiogram was continuously recorded for 15 min at rest and for 4 min in the deep breathing test, with a breath rate of 5 to 6 cycles/min in the supine position. Resting HR and RR intervals were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components are reported in normalized units (nu) at low (LF) and high (HF) frequency, and as the LF/HF ratio. The deep breathing test was analyzed by the respiratory sinus arrhythmia indices: expiration/inspiration ratio (E/I) and inspiration-expiration difference (deltaIE). The active groups had lower HR and higher RMSSD index than the sedentary groups (life-style condition: sedentary vs active, P < 0.05). The older groups showed lower HFnu, higher LFnu and higher LF/HF ratio than the young groups (aging effect: young vs older, P < 0.05). The OS group had a lower E/I ratio (1.16) and deltaIE (9.7 bpm) than the other groups studied (YS: 1.38, 22.4 bpm; YA: 1.40, 21.3 bpm; OA: 1.38, 18.5 bpm). The interaction between aging and life-style effects had a P < 0.05. These results suggest that aging reduces HR variability. However, regular physical activity positively affects vagal activity on the heart and consequently attenuates the effects of aging in the autonomic control of HR.

Adult↗

PubMed2001

Trypanosoma cruzi: peripheral blood monocytes and heart macrophages in the resistance to acute experimental infection in rats.

The contribution of mononuclear phagocytes to host resistance against acute Chagas disease has been studied in vivo in a rat model inoculated with Trypanosoma cruzi, Y strain. Acute T. cruzi infection triggered a dramatic increase (937%) in peripheral blood monocyte number at day 12 of infection. At this point, histological analysis of the heart showed high parasitism and diffuse and a moderate to intense mononuclear inflammatory process. Ultrastructural study revealed a large number of macrophages, in addition to lymphocytes and undiffer entiated cells. Clusters of macrophages exhibited different morphologi cal phenotypes, with evident signs of activation (increase in size, surface rufflings, and amount of cytoplasmic organelles). Cell-to-cell contacts involving macrophages and lymphocytes or macrophages and mono cytes were observed. Depletion of macrophages by treatment with silica, a selective cytotoxic agent for these cells, caused a significant increase in the number of amastigote nests in cardiomyocytes. The present findings indicate that the early phase of infection with T. cruzi induces rapid production, maturation, and activation of the monocyte/macrophage system so as to control T. cruzi replication, emphasizing the crucial role for macrophages in the rat resistance to Chagas disease.

Animals↗

PubMed1999

Depletion of immune effector cells induces myocardial damage in the acute experimental Trypanosoma cruzi infection: ultrastructural study in rats.

The contribution of radiosensitive cells and macrophages to myocardial immunopathology has been studied in rats inoculated with Trypanosoma cruzi, Y strain. Immunodepression was induced by gamma irradiation and depletion of radioresistant macrophages was achieved by silica, a selective cytotoxic agent for macrophages. Irradiated or silica treated rats and age-matched controls were sacrificed at day 12 of infection so as to study the heart by light and electron microscopy. In the infected controls, damaged cardiomyocytes were directly related to tissue parasitism; inflammatory cells, predominantly lymphocytes and macrophages, were present. The drastic depletion of radiosensitive cells (lymphocytes and granulocytes), as well as the depletion of macrophages by silica, induced cardiomyocytes damage during the acute infection, exacerbating the lesions seen in the infected controls. In the irradiated-infected and silica treated-infected animals, degenerating cardiomyocytes, parasitized or not, were frequently observed, displaying evident signs of cytoplasmic and nuclear damage. Some signs of cardiomyocyte damage (irregular distribution of glycogen particles and myofibrils with shrinkage and aggregation of Z bands) were present only in silica treated-infected animals. The findings suggest that immune effector cells may not play a major role in the cardiomyocyte damage induced by acute. Chagas disease, arguing against the autoimmune etiology of Chagasic cardiomyopathy.

Animals↗

PubMed1998

Depletion of radiosensitive leukocytes exacerbates the heart sympathetic denervation and parasitism in experimental Chagas' disease in rats.

The acute phase of the Trypanosoma cruzi infection induces damage of the heart sympathetic nerve terminals in rats. The participation of the radiosensitive leukocytes in this process was assessed in young rats submitted to gamma irradiation 1 day before infection with T. cruzi, Y strain. Gamma irradiation increased the heart noradrenergic denervation evaluated at day 12 of infection by histochemical and electron-microscopic methods. The presence of numerous macrophages with ultrastructural features of activation and a significant rise in the myocardial parasitism suggest the involvement of radioresistant macrophages or parasite factors, or both, on the damage of the nerve terminals.

Animals↗

PubMed1993

Noradrenergic and acetylcholinesterase-positive nerve fibres of the uterus in sexually immature and cycling rats.

The distribution and density of the noradrenergic and acetylcholinesterase-positive nerve fibres were histochemically studied in different uterine regions of prepubertal and cycling rats in dioestrus and oestrus. Besides the rich and double innervation of blood vessels, both types of nerve fibre were found in the myometrium and cervical musculature. The non-vascular noradrenergic network looked denser at the tubal end of the horns and at the cervix, whereas the acetylcholinesterase-positive innervation was poor at the tubal end, increasing toward the cervix. Contrasting with the middle third of the uterine horn, at the tubal end, the myometrial longitudinal layer was much more innervated than the circular one, especially by the noradrenergic nerve fibres. The prepubertal rats presented an adult pattern of uterine autonomic innervation. In the cycling animals, this innervation was nearly the same during oestrus and dioestrus regarding both the density of nerve fibres and intensity of the histochemical reactions.

Acetylcholinesterase↗

PubMed1978

Tissue tropism of different Trypanosoma cruzi strains.

A systematic study of the distribution of intracellular parasites in the organs and tissues was performed in groups of mice inoculated with 4 different Trypanosoma cruzi strains. An extremely high parasitism of spleen, liver, and bone marrow was observed in mice inoculated with Y and Berenice strains; with CL strain, however, parasites were almost absent in those organs. Bloodstream forms apparently present differences which facilitate or prevent their uptake by macrophages from the mononuclear phagocytic system. Parasitism of the smooth muscle from hollow organs was significantly higher with ABC and Berenice strains than with Y and CL. The importance of the distribution of intracellular stages in the pathogenesis of the disease is discussed.

Animals↗

PubMedDate not supplied

[Relapse on Kawasaki disease]

OBJECTIVES: to draw the pediatrician's attention to the characteristics, the diagnostic criteria and the possibility of relapse of the acute phase of the Kawasaki disease with its possible complications. METHOD: case report of a patient registered at Hospital Universitário de Brasília under medical record number 400682 and review of the literature. RESULTS: Case report of a boy who relapsed the clinical aspects of the disease, after disappearance of signs and symptoms of the acute phase, and who complicated with aneurysm of the left coronary artery. CONCLUSION: the diagnosis of Kawasaki Disease is based on clinical findings. The pediatrician should be always alert to the diagnostic criteria since this is a disorder that may lead to heart complications following the acute phase or after its recurrence. These cardiac complications may lead to death in 2% of the patients.

Journal Article↗